1. Field of the Invention
The present invention relates generally to the field of fossil fuels and in particular to methods and compounds for increasing the viscosity and reducing the dispersion of bitumen-in-water emulsions following spills or leaks, and specifically with regard to a bitumen-in-water emulsion known as ORIMULSION, produced by and a trademark of Petroleos di Venezuela.
2. Description of the Related Art
ORIMULSION is a well-known alternative fossil fuel that can be combusted by industrial power plants which have been modified for the fuel. See, for example, Makansi, J., "Manatee Lays Groundwork for Commercial Use of Orimulsion," Power, September 1994, pp. 57-60; Makansi, J., "New Fuel Could Find Niche Between Oil, Coal," Power, December 1991, pp. 51-56. ORIMULSION consists of approximately 70% bitumen droplets dispersed in about 30% water, with a small amount of surfactant added to stabilize the emulsion. Bitumen is an extra heavy crude oil with an API gravity density of less than 8.degree.. ORIMULSION is much less viscous than bitumen, and as a result, ORIMULSION may be transported by conventional pipelines and in tankers. For a particular sample tested, the pH of ORIMULSION is about 8.09, the density is about 0.995 and the wt % moisture of ORIMULSION is about 32.65.
A significant concern with the use and transport of ORIMULSION is that it is readily dispersable in water. Thus, if spills occur on land or at sea, the ORIMULSION can quickly spread over a large area in a short time, rapidly causing greater environmental damage.
It has been reported that when the ORIMULSION dispersion is reversed, that is, to a water-in-bitumen mixture (water droplets dispersed in bitumen), it has a viscosity near to that of bitumen. The following conditions may cause this inversion, or reversal, in ORIMULSION:
1) exposure to temperatures exceeding 176.degree. F.; 2) sudden pressure drop exceeding 100 psi; 3) centrifugal pump shearing at greater than 1800 rpm; and 4) mixing with greater than 1% #6 oil, which can occur during fuel switching.
Since ORIMULSION is a multi-component, two-phase system, this type of emulsion and its physical properties can be changed by changing the composition of the components, adding other chemicals, or changing the conditions surrounding the system.